Vesicular stomatitis virus (VSV), a member in the rhabdovirus family, causes a contagious disease in horses, cattle and pigs, characterized by lesions in the oral mucosa and udder. During the past few years, severe outbreaks of the disease in the United States, Mexico and parts of Central and South America produced substantial economic losses. There is also public health concern because humans can be infected, Patterson, W. C., et al., J. Am. Vet. Med. Ass., 133, 57 (1958), and the virus may be spread by insect vectors, Ferris et al., J. Infect. Dis., 96, 184 (1955), Tesh et al., Science, 175, 1477 (1972). Experimental attenuated and inactivated whole VSV vaccines provide some protection to animals; however, their use is usually not permitted by some governmental regulatory agencies, such as the United States Department of Agriculture, because of the inability to distinguish vaccinated animals from those naturally infected. Such a distinction could be made if subunit vaccines were developed. Moreover, subunit vaccines would eliminate the dangers associated with incomplete inactivation of VSV or the reversion of attenuated virus to virulence. However, whether use of subunit vaccines would be protective and economically feasible remains to be determined.
The approach taken in this invention to VSV immunization is to produce a synthetic vaccine in the form of a recombinant virus by inserting a nucleotide sequence corresponding to a segment of the VSV viral genome into a virus that is nonpathogenic to the vaccinated animal so that a VSV protein or protein segment is expressed by the recombinant virus. In particular, the invention inserts a DNA sequence corresponding to a segment of the VSV RNA genome into the vaccinia viral DNA genome, whereby the recombinant vaccine virus functions as a vaccine when innoculated into a VSV-susceptible animal.
The development of vaccinia virus as an infectious eukaryotic cloning vector (D. Panicali et al., Proc. Natl. Acad. Sci. USA, 79, 4927 (1982); M. Mackett et al., Proc. Natl. Acad. Sci. USA, 79, 7415 (1982); and M. Mackett et al., J. Virol., 49, 857 (1984)) provides an alternative to whole virus or subunit vaccines. Heterologous genes, including hepatitis B virus surface antigen (G. L. Smith et al., Nature (London), 302, 490 (1983); G. L. Smith et al., UCLA Symposia on Molecular and Cellular Biol., New Series 8, 543 (1983); E. Paoletti et al., Proc. Natl. Acad. Sci. USA, 81, 193 (1984)), influenza virus hemagglutinin (D. Panicali et al., Proc. Natl. Acad. Sci. USA, 80, 5364 (1983), G. L. Smith et al., Proc. Natl. Acad. Sci. USA, 80, 7155 (1983)), herpes virus glycoprotein D (E. Paoletti et al., Proc. Natl. Acad. Sci. USA, 81, 193 (1984)), and malaria sporozoite surface antigen (G. L. Smith et al., Science, 224, 397 (1984)) have been expressed in this vector system. In several cases, vaccination has protected experimental animals against challenge with the corresponding pathogen. Perhaps because of the historical use of vaccinia virus as a smallpox vaccine, attention has focused on human applications. However, the presumed origin of vaccinia virus from cowpox and its ability to infect a variety of domesticated animals raises the possibility of veterinary uses as well.
VSV contains a single negative strand of RNA which encodes 5 known proteins. Two VSV serotypes, Indiana (VSV.sub.I) and New Jersey (VSV.sub.NJ), are known. Although the diseases caused by the two VSV serotypes are similar, they are immunologically distinct and are found in separate enzootic areas within the Western Hemisphere. Complementary DNA copies of mRNA for the G, M, N, and NS proteins of VSV.sub.I have been cloned and sequenced (J. K. Rose et al., J. Virol., 39, 519 (1981); C. J. Gallione et al., J. Virol., 39, 529 (1981); C. J. Gallione et al., J. Virol., 46, 162 (1983). The G and N genes of the Indiana serotype have been expressed in eukaryotic cells (J. K. Rose et al., Cell, 30, 753 (1982); J. Sprague et al., J. Virol., 45, 773 (1983)). The sequence of the VSV.sub.NJ virus is reported in Gallione, C. J. and Rose, J. K., Journal of Virology 46, 162-169 (1983). This article also reports the isolation of VSV.sub.NJ cDNA, including that corresponding to the genome segment which encodes the G protein.